My kitchen flooring consists of a click-type wood floor laid on top of an old vinyl layer, which again rests on concrete. After tearing down the previous owner's kitchen, I learned that the cabinets, stove and sink rested on the concrete and had none of the wood (or vinyl) flooring underneath them. The new kitchen furniture will cover all the now exposed concrete, as well as parts of the wood not covered by the old furniture. The furniture to be installed has some adjustability for uneven flooring, but not enough for the approximately 3 cm difference between the concrete and the wood.

I'd rather not re-lay the entire floor, if I can avoid it. The wood is in great condition, and I'm not sure I could find the exact same type to simply complete it. It also feels like a waste of money to floor an area that will be fully hidden by kitchen furniture. To me, the obviously simplest way to prepare for the new furniture seems to be lay down wooden boards approximately 3 cm thick for the legs of the new furniture to stand on. I am, however, afraid that perhaps the wood will compress very differently from the wood floor, causing problems. Is this a legitimate worry? Does anyone have any ideas on how I should procede? Should I perhaps use floor planks of a similary type as used for the floor instead of just simple wooden boards?

I hope I've been sufficiently clear in my description, and that someone has some tips for me.

Below is a sketch of the kitchen.

Brown: wood floor.

Grey: exposed concrete approximately 3 cm below wood floor.

Transparent red: extent of kitchen furniture to be installed.

Black outline: illustration of the wood board suggestion described above.

2 Answers
2

If it's not visible, just got for a manufactured board, e.g. plywood, OSB, etc. For 3cm, you may be looking at two pieces stacked on top of each other. If it's on concrete, install a moisture barrier first. To secure the boards, I'd avoid the temptation to use a Ramset and permanently drive the names into the cement, since the next time the flooring is redone, you can take the opportunity to do it right and pull everything up and go wall to wall. Instead, secure it with a few cut nails. Again, this all assumes that none of this is visible.

Cut nails are used when going into concrete. A regular nail will just bend. Just realize that the cut nail can shatter, so wear safety glasses when hammering them in.
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BMitch♦May 12 '11 at 18:09

Also, compared to a Ramset nail, if you don't over hammer it, you can get a cut nail back out. After a Ramset shoots a nail in, it's next to impossible to get back out.
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BMitch♦May 12 '11 at 18:11

Good to know. So you mean hand-driven concrete nails, not just any old cut nails (which also includes, e.g., soft-steel nails that have a slim head and a square profile).
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Alex FeinmanMay 12 '11 at 18:24

Until you said that, I didn't realize there was another type of cut nail. I've updated the picture for what we typically use at the job site. Thanks!
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BMitch♦May 12 '11 at 18:30

I wouldn't over invent to solution, which you already gave. If you cut out wood pieces that fit inside the low parts and place the furniture on that, you will be fine. The wood won't slip or move because it's contacting all the sides of the "hole". Just get enough wood in there to make it level with the surrounding floor, and adjust the furniture from. As to the compression of the wood, I have never noticed plywood or hard wood flooring flatten from furniture weight. Old wood houses sag because there is no concrete, and the joists are not secure enough. You have neither of these problems. I would award the answer to you.